The purpose of this research is to determine whether removal of prefontal cortex in infant rats allows behavioral sparing of function under conditions similar to those in which sparing occurs in rhesus monkeys. Current research has shown that sparing in rats occurs after both medial and orbital frontal lesions but that it is dependent on the task, the sex of the animal, and age at surgery. During the next year we will extend these studies to several additional tasks: DRL, bar press extinction, and delayed alternation. In addition the effects of prefrontal lesions during infancy on delayed alternation will be compared with the effects of seriatim prefrontal lesions in adults on this same task.